4l60e extremly hard 1-2 shift

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name

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Hi Guys,

I have a new to me 1994 GMC Suburban K1500 with 104,000 miles on it. The previous owner used it for towing and told me it had a trans rebuild and a shift kit added less than 20k miles ago. when I test drove it and asked about the hard shift he said it was because of the shift kit, not ever having anything with a shift kit in it I didn't think much about it . when I ask what kind of kit was in it he didn't know, just said the shop put it in.

HOWEVER , after buying it I find that the 1-2 shift is so hard that I am afraid it will break something, the shift is always at 1500 rpm and always immediate, with no lag. The 2-3 shift is firmer than anything else I have driven but acceptable. the rest of the shifting seems normal .


Right now it is just sitting because after reading many threads I don't want to cause any damage that would require pulling the trans. Is there any common problem with this 1-2 hard shift symptom that I should look at ?

Many Thanks,
 

someotherguy

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There are some problems that can cause this. A weak, broken, or incorrect 1-2 accumulator spring, or a leaking seal on the accumulator's piston.. time to have an experienced transmission person check it out. They'll likely pull the pan and valve body and see what's going on. This can be done with the transmission still in the truck.

Richard
 

deadbeat

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After having my 4L60E rebuilt it shifted hard from 1-2, the shop told me they could tone it down some but did not recommend it. I may have it wrong but I think it had something to do with an added shift kit, IIRC.
 

someotherguy

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After having my 4L60E rebuilt it shifted hard from 1-2, the shop told me they could tone it down some but did not recommend it. I may have it wrong but I think it had something to do with an added shift kit, IIRC.
It can definitely shift TOO hard. You wouldn't think that until you've driven one that is doing it, though. Even part throttle 1-2 shift that snatches the driveline so hard you're worried it's gonna break a U-joint or chip teeth off the ring & pinion...ugh

Richard
 

df2x4

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It can definitely shift TOO hard. You wouldn't think that until you've driven one that is doing it, though. Even part throttle 1-2 shift that snatches the driveline so hard you're worried it's gonna break a U-joint or chip teeth off the ring & pinion...ugh

Richard

Billet servos and a TransGo HD2 plus maxed shift firmness and no torque management in the tune (terrible idea) was enough to put a crack in the otherwise pristine dash of my red truck from a WOT 1-2 shift.
 

name

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Pulled the codes today with a paper clip : 32 and 73

From what I can tell they are BARO / EGR / MAP and and AC evaporater and should not have anything to do with a hard 1-2 shift. Is this correct ?

Is there another procedure to pull the trans codes or will they pull with the engine codes ?
 

name

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I did take it to a tranny shop today but they could not get to it, I will have to drop it off sometime next week for them to look at it .

I don't understand why you would want to put a shift kit into a suburban when you just had it rebuilt , is there some sort of logic to doing this ?
 

df2x4

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I don't understand why you would want to put a shift kit into a suburban when you just had it rebuilt , is there some sort of logic to doing this ?

Fairly common, sort of a "while you're in there" type of thing if you want the vehicle to feel a little more aggressive. I've had a TransGo HD2 shift kit installed in every GM automatic transmission that I've had rebuilt.
 

name

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Just got a call from the tranny guy, he said he hooked a computer up but could not connect to the EPC. He is going to drop the pan tomorrow to do further testing.

$150. and counting...
 

name

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just got the Suburban back from the trans guy, this is what the tech who did the work told me :

They could not connect to the EPC with the computer so they dropped the pan to check the wiring, when they did they found that the EPC was un-pluged. This was the first time he found one simply unplugged, but it did snapped firmly back in place so they made no other adjustments or corrections. When I asked if he could tell if it was rebuild or in fact did have a shift kit in it like the previous owner told me he said that there was no way to tell for sure just buy dropping the pan, but everything was so clean that he did not doubt it was at least serviced . He said that it is possable that whoever did the work before simply forgot to plug it back in.

Here are some of my questions I have for the forum :

1 ) If the EPC was un-pluged for 20k miles what damage would it of caused ? ( I am Assumng that it was rebuilt 20k miles ago)

2 ) The Suburban shifts so smooth now that most of the time I can not tell without looking at the tach, is this normal for this tranny ? ( with or without a shift kit )

3 ) is there any condition that could of caused the EPC to become unplugged other than human error ?

Total bill for all of this is $354. seems a little high to me for just dropping a pan and connecting a plug, but what do I know .

Any other opinions / suggestions are welcome...
 
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